This story aired on the November 19 2024 episode of Crosscurrents
Fifty years ago, developers planned to flatten the top of San Bruno Mountain, dump 350 million cubic yards of rock into the bay, and build a housing development.
That was until a movement to preserve the land as open space and protect multiple endangered species halted most construction. What can the story of San Bruno Mountain tell us about the relationship between environmentalism and housing?
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Evan Cole, the Natural Resource Manager for San Mateo County Parks, is listing off the species on San Bruno Mountain: “We have coyotes, brush rabbits, a variety of snakes, and then of course our very unique insects,” he says.
Today he’s searching for the elusive San Bruno Elfin butterfly. It's his job to count the endangered butterflies here at San Bruno Mountain in Brisbane and to track how their populations are doing. But Elfin can be hard to find in the scrubby brush.
“They don't look as obviously charming as the Mission Blue butterfly,” Evan says.
The Mission Blue is electric blue. The Elfin is small and brown, kind of like a moth. So it blends in. But in its caterpillar form — which is how we'll see it today — it's lipstick red, juicy, and beautiful.
The San Mateo Parks Department counts them every two years, so today we’re on a quest. The quest starts with sedum.
Sedum is the succulent host plant for the caterpillars. Evan and his team construct circular plots around its habitat and count as many as they can find. These counts help them estimate the mountain’s overall population.
We’re up at Dairy Ravine Trail on San Bruno Mountain. It slopes into wildland on one side and a bustling Guadalupe Canyon Parkway on the other.
“This is maybe our most unhidden, hidden gem of a park, with everybody driving by it between SFO and San Francisco,” says Evan.
It’s also where the final car chase in the 1960s movie, Bullitt, was filmed with Steve McQueen.
But San Bruno Mountain has played many roles beyond its cinematic one. The Ohlone people, who have lived in Northern California Coastal areas for thousands of years, once called the valleys of San Bruno Mountain home. After Europeans arrived and displaced them, the land was ranched with cattle.
Today, there’s a major highway in front of us, planes flying overhead, and radio and broadcast towers rising out of the land. But it’s a surprising oasis, home to swaths of birds, endangered plants, and insects.
Evan says when he learned to recognize birdsong, his life exploded in color.
“You start to open your eyes to this whole community around you,” he says. “And I think that's kind of the way it is with butterflies. There's something really special about butterflies that are only found here, only found in this county.”
Evan says the Elfin is a jewel of the mountain the way the mountain is a jewel of the county.
“It's become restricted by all this development, but it's still holding its ground, and there's a lot of people that are really passionate about keeping it,” he says.
There’s development all around the mountain, but Evan says environmentalists have managed to protect it and mostly preserve its natural state. This is despite the construction of a major highway in 1968 when developers had big plans to flatten the mountain and to build a neighborhood on it.
The area was so notorious for booming development that Malvina Reynolds even wrote the classic song “Little Boxes” about it.
But anyone who’s driven by this wild sloping piece of land can tell you those plans were never realized. The reason is partly because of a people’s movement that started in the 1970s. David Schooley was one of its leaders.
“It was oak forest, untouched, just shining, oak trees, isle, forest, grasses, everything, this incredible thing,” says David thinking back to his first time seeing San Bruno Mountain fifty years ago. “I went up into Buckeye Canyon. No trail. I just couldn't believe it. And that began my whole life.”
Shortly after David first saw the mountain, he learned it would soon be transformed into a housing development with stores and apartment buildings constructed for thousands of people.
This activated David, an environmentalist who once made a pact never to drive a car. It was his way of protesting the construction of a highway. Decades later, he’s kept that promise. And it was with that same passion that he set out to protect San Bruno Mountain.
“All of us were horrified because people who lived in Brisbane, Brisbane was a secret because of the oak forest and the wilderness above it,” says David.
Alongside community members from Brisbane, and environmental organizations like Save the Bay, David helped start a movement called the Committee to Save San Bruno Mountain to stop the development and fight for a public park.
The movement was successful in blocking much of the planned construction. A 1978 lawsuit was settled with the county taking over about half of the mountain to protect it. A couple of years later, the state took over some acres in the mountain’s saddle area, a lower elevation point between the peaks.
But that’s not where this story ends. Developers were still planning to build on the private land.
“And this started a whole new war,” says David. “War number one was the saddle and the people, and then it was the butterflies and the town itself.”
The site already had residents — the endangered Mission Blue butterfly and the San Bruno Elfin butterfly. They’d been added to the brand new Endangered Species Act in 1976 so their habitat — right where developers wanted to build — was protected.
“We thought, hey, this is a miracle,” says David. “Number one, we saved the mountain, now butterflies are going to save the mountain, they're going to stop the builders.”
But that’s not exactly what happened. Instead, developers were only temporarily stalled. Then, in 1982, the Endangered Species Act was amended to allow for the “limited and unintentional take of endangered species.”
Basically, this means it’s legal to build on endangered species habitat with a Habitat Conservation Plan or HCP in place.
Today there are several hundred HCPs around the country, but the one on San Bruno Mountain was the first. To people, like David, the HCP program is a catastrophic failure.
“That shouldn't happen. Rare and endangered species should be given pure care and concern,” he says.
But others consider the HCP program a necessary compromise and point to the fact that they require landowners to commit to species conservation in order to build.
In fact, the reason Evan and his team count the butterflies is because of an HCP mandate. Today, the mountain is a patchwork of state, county, and private owners.
And as for David’s people’s movement, it developed into San Bruno Mountain Watch, an organization that cares for the mountain through ecological restoration and advocacy.
The HCP debate raises the question: in the Bay Area, where housing is scarce and natural space is beloved, can we fight for both simultaneously?
“I think they're inextricably tied together,” says Jordan Grimes who works on state and regional housing policy with Greenbelt Alliance, an environmental and housing nonprofit.
“We cannot solve our climate crisis without solving our housing crisis and vice versa,” he says. “Both things are wrapped up in how we use our land. It's the single most important thing affecting the Bay Area today.”
To Jordan the framing of “conservation versus housing development” is problematic. Instead, he says we need to build in a very different way — more densely and in existing urban areas.
“We need to embrace infill and embrace building taller and denser in our existing cities,” says Jordan. “So that that butterfly can continue to exist. And so that person doesn't end up on the street.”
In San Mateo this would mean loosening zoning barriers to allow for higher and denser buildings. But it would also mean that not everyone gets their own private patch of green space. Jordan sees this proposed change in mindset around how we live as a way to protect open space.
“For me, enjoying time on San Bruno Mountain means looking across the rest of the county, and seeing how much potential and how much work we still have to do,” he says. “We have a responsibility to accommodate people in a sustainable way.”
And we have a responsibility to care for precious open space. In addition to four species of endangered or threatened butterflies on the mountain, it’s also home to a dozen rare and endangered plant species.
Back on the mountain, we’re looking for signs of the Elfin.
“You can often see some windowing, we call it,” says Evan referring to places the caterpillars chew through leaves. “That gives you a sign that there are larvae here that you can find.”
And then, we see it, the reason we’ve come here today: “See on the tip of the flower there,” says Evan pointing. On top of a spring green succulent with little yellow flowers, we find a tiny red caterpillar.
Despite some habitat degradation on the mountain, Evan’s team counted over a thousand Elfin larvae this year, similar to the previous two counts.
If these Elfin survive, they’ll enter a hibernation-like state and in February, emerge as butterflies.
If you're interested in taking a guided hike of San Bruno mountain, check out San Bruno Mountain Watch
